A motor vehicle generally utilizes a driveline containing propshafts to connect the transmission or power takeoff unit to the driving wheels. Propshafts may become rotationally unstable if operated at the rotational speed where the propshaft residual balance forces coincide with the propshaft natural bending resonance.
At certain rotational speeds and resonant frequencies the above-referenced propshafts typically exhibit unbalanced rotation and thus undesirable vibrations. These vibrations traditionally result in bending or torsional forces within and along the length of the respective propshaft. Such bending or torsional forces, as a result of the unbalanced rotation, are neither desirable nor suitable in the operation of the driveline systems of most vehicles. Additionally, vibrations from the engine or transmission may be undesirably transmitted through the propshafts.
Accordingly, various dynamic dampers or mass dampers are utilized to suppress the undesirable vibrations, whether induced in the rotary propshaft due to the unbalanced rotation or transmitted through the propshaft. These dampers are often installed or inserted directly onto or into the propshaft. The dampers are designed to generate a prescribed vibrational frequency adjusted to the dominant frequency of the undesired vibrations. The damper converts or transfers the vibrational energy of the propshaft to the damper by resonance, and eventually absorbs the vibrational energy of the propshaft. Therefore, the damper attempts to cancel or negate the vibrations that are induced onto or caused by the rotary propshaft in normal operation of the driveline system of the vehicle.
Many dampers generally include a mass member disposed between a pair of ring-shaped fixing members and a pair of connecting members. The connecting members connect the ends of the fixing members to the mass members. However, many of these traditional dampers are not easily tunable to specific frequencies and have difficulty controlling damping without extensive redesign of the damper and the propshaft for each automotive vehicle driveline system. Further, many traditional dampers include other mass members cantilevered from a connecting member. These mass members, essentially suspended from a theoretical spring, introduce an additional degree of freedom into the system thus producing another resonance.
Therefore, there is a need in the art for an improved internal absorber. There also is a need in the art for an internal absorber that does not use a cantilevered mass to create a dampening effect. There also is a need in the art for an internal absorber that is simple to install and modify to match specific frequencies and dampening levels of various vehicle driveline systems.